X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Frunas.c;h=1105f207fb83d3b4ef1734159fbd7a7e0e0a3f04;hp=bee107951d8664e6f111ed5ff260574407f0c3a3;hb=5b5bb8c82d70cf65707d5561e0640bf2ae8c2e6e;hpb=373d38732a83167f19c3be89cf9ff238743cdeb0

diff --git a/src/common/runas.c b/src/common/runas.c
index bee107951..1105f207f 100644
--- a/src/common/runas.c
+++ b/src/common/runas.c
@@ -2,21 +2,22 @@
  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License as published by the Free
- * Software Foundation; only version 2 of the License.
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2 only,
+ * as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  * more details.
  *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
- * Place - Suite 330, Boston, MA  02111-1307, USA.
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <errno.h>
 #include <limits.h>
 #include <stdio.h>
@@ -29,291 +30,717 @@
 #include <fcntl.h>
 #include <sched.h>
 #include <sys/signal.h>
+#include <assert.h>
+#include <signal.h>
 
-#include <common/error.h>
-#include <common/compat/mman.h>
-#include <common/compat/clone.h>
+#include <common/common.h>
+#include <common/utils.h>
+#include <common/compat/getenv.h>
+#include <common/compat/prctl.h>
+#include <common/sessiond-comm/unix.h>
 
 #include "runas.h"
 
-#define RUNAS_CHILD_STACK_SIZE	10485760
+struct run_as_data;
+typedef int (*run_as_fct)(struct run_as_data *data);
 
-#ifndef MAP_STACK
-#define MAP_STACK		0
-#endif
+struct run_as_mkdir_data {
+	char path[PATH_MAX];
+	mode_t mode;
+};
+
+struct run_as_open_data {
+	char path[PATH_MAX];
+	int flags;
+	mode_t mode;
+};
+
+struct run_as_unlink_data {
+	char path[PATH_MAX];
+};
+
+struct run_as_rmdir_recursive_data {
+	char path[PATH_MAX];
+};
+
+enum run_as_cmd {
+	RUN_AS_MKDIR,
+	RUN_AS_OPEN,
+	RUN_AS_UNLINK,
+	RUN_AS_RMDIR_RECURSIVE,
+	RUN_AS_MKDIR_RECURSIVE,
+};
 
 struct run_as_data {
-	int (*cmd)(void *data);
-	void *data;
+	enum run_as_cmd cmd;
+	union {
+		struct run_as_mkdir_data mkdir;
+		struct run_as_open_data open;
+		struct run_as_unlink_data unlink;
+		struct run_as_rmdir_recursive_data rmdir_recursive;
+	} u;
 	uid_t uid;
 	gid_t gid;
-	int retval_pipe;
 };
 
-struct run_as_mkdir_data {
-	const char *path;
-	mode_t mode;
+struct run_as_ret {
+	int ret;
+	int _errno;
 };
 
-struct run_as_open_data {
-	const char *path;
-	int flags;
-	mode_t mode;
+struct run_as_worker {
+	pid_t pid;	/* Worker PID. */
+	int sockpair[2];
+	char *procname;
 };
 
+/* Single global worker per process (for now). */
+static struct run_as_worker *global_worker;
+/* Lock protecting the worker. */
+static pthread_mutex_t worker_lock = PTHREAD_MUTEX_INITIALIZER;
+
+#ifdef VALGRIND
+static
+int use_clone(void)
+{
+	return 0;
+}
+#else
+static
+int use_clone(void)
+{
+	return !lttng_secure_getenv("LTTNG_DEBUG_NOCLONE");
+}
+#endif
+
+LTTNG_HIDDEN
+int _utils_mkdir_recursive_unsafe(const char *path, mode_t mode);
+
 /*
  * Create recursively directory using the FULL path.
  */
 static
-int _mkdir_recursive(void *_data)
+int _mkdir_recursive(struct run_as_data *data)
 {
-	struct run_as_mkdir_data *data = _data;
 	const char *path;
-	char *p, tmp[PATH_MAX];
-	struct stat statbuf;
 	mode_t mode;
-	size_t len;
-	int ret;
 
-	path = data->path;
-	mode = data->mode;
-
-	ret = snprintf(tmp, sizeof(tmp), "%s", path);
-	if (ret < 0) {
-		PERROR("snprintf mkdir");
-		goto error;
-	}
-
-	len = ret;
-	if (tmp[len - 1] == '/') {
-		tmp[len - 1] = 0;
-	}
-
-	for (p = tmp + 1; *p; p++) {
-		if (*p == '/') {
-			*p = 0;
-			ret = stat(tmp, &statbuf);
-			if (ret < 0) {
-				ret = mkdir(tmp, mode);
-				if (ret < 0) {
-					if (!(errno == EEXIST)) {
-						PERROR("mkdir recursive");
-						ret = -errno;
-						goto error;
-					}
-				}
-			}
-			*p = '/';
-		}
-	}
+	path = data->u.mkdir.path;
+	mode = data->u.mkdir.mode;
 
-	ret = mkdir(tmp, mode);
-	if (ret < 0) {
-		if (!(errno == EEXIST)) {
-			PERROR("mkdir recursive last piece");
-			ret = -errno;
-		} else {
-			ret = 0;
-		}
-	}
+	/* Safe to call as we have transitioned to the requested uid/gid. */
+	return _utils_mkdir_recursive_unsafe(path, mode);
+}
 
-error:
-	return ret;
+static
+int _mkdir(struct run_as_data *data)
+{
+	return mkdir(data->u.mkdir.path, data->u.mkdir.mode);
 }
 
 static
-int _mkdir(void *_data)
+int _open(struct run_as_data *data)
 {
-	struct run_as_mkdir_data *data = _data;
-	return mkdir(data->path, data->mode);
+	return open(data->u.open.path, data->u.open.flags, data->u.open.mode);
 }
 
 static
-int _open(void *_data)
+int _unlink(struct run_as_data *data)
 {
-	struct run_as_open_data *data = _data;
-	return open(data->path, data->flags, data->mode);
+	return unlink(data->u.unlink.path);
 }
 
 static
-int child_run_as(void *_data)
+int _rmdir_recursive(struct run_as_data *data)
 {
-	struct run_as_data *data = _data;
-	size_t writelen, writeleft, index;
-	union {
-		int i;
-		char c[sizeof(int)];
-	} sendret;
-	int ret;
+	return utils_recursive_rmdir(data->u.rmdir_recursive.path);
+}
 
-	/*
-	 * Child: it is safe to drop egid and euid while sharing the
-	 * file descriptors with the parent process, since we do not
-	 * drop "uid": therefore, the user we are dropping egid/euid to
-	 * cannot attach to this process with, e.g. ptrace, nor map this
-	 * process memory.
-	 */
-	if (data->gid != getegid()) {
-		ret = setegid(data->gid);
+static
+run_as_fct run_as_enum_to_fct(enum run_as_cmd cmd)
+{
+	switch (cmd) {
+	case RUN_AS_MKDIR:
+		return _mkdir;
+	case RUN_AS_OPEN:
+		return _open;
+	case RUN_AS_UNLINK:
+		return _unlink;
+	case RUN_AS_RMDIR_RECURSIVE:
+		return _rmdir_recursive;
+	case RUN_AS_MKDIR_RECURSIVE:
+		return _mkdir_recursive;
+	default:
+		ERR("Unknown command %d", (int) cmd)
+		return NULL;
+	}
+}
+
+static
+int do_send_fd(struct run_as_worker *worker,
+		enum run_as_cmd cmd, int fd)
+{
+	ssize_t len;
+
+	switch (cmd) {
+	case RUN_AS_OPEN:
+		break;
+	default:
+		return 0;
+	}
+	if (fd < 0) {
+		return 0;
+	}
+	len = lttcomm_send_fds_unix_sock(worker->sockpair[1], &fd, 1);
+	if (len < 0) {
+		PERROR("lttcomm_send_fds_unix_sock");
+		return -1;
+	}
+	if (close(fd) < 0) {
+		PERROR("close");
+		return -1;
+	}
+	return 0;
+}
+
+static
+int do_recv_fd(struct run_as_worker *worker,
+		enum run_as_cmd cmd, int *fd)
+{
+	ssize_t len;
+
+	switch (cmd) {
+	case RUN_AS_OPEN:
+		break;
+	default:
+		return 0;
+	}
+	if (*fd < 0) {
+		return 0;
+	}
+	len = lttcomm_recv_fds_unix_sock(worker->sockpair[0], fd, 1);
+	if (!len) {
+		return -1;
+	} else if (len < 0) {
+		PERROR("lttcomm_recv_fds_unix_sock");
+		return -1;
+	}
+	return 0;
+}
+
+/*
+ * Return < 0 on error, 0 if OK, 1 on hangup.
+ */
+static
+int handle_one_cmd(struct run_as_worker *worker)
+{
+	int ret = 0;
+	struct run_as_data data;
+	ssize_t readlen, writelen;
+	struct run_as_ret sendret;
+	run_as_fct cmd;
+	uid_t prev_euid;
+
+	/* Read data */
+	readlen = lttcomm_recv_unix_sock(worker->sockpair[1], &data,
+			sizeof(data));
+	if (readlen == 0) {
+		/* hang up */
+		ret = 1;
+		goto end;
+	}
+	if (readlen < sizeof(data)) {
+		PERROR("lttcomm_recv_unix_sock error");
+		ret = -1;
+		goto end;
+	}
+
+	cmd = run_as_enum_to_fct(data.cmd);
+	if (!cmd) {
+		ret = -1;
+		goto end;
+	}
+
+	prev_euid = getuid();
+	if (data.gid != getegid()) {
+		ret = setegid(data.gid);
 		if (ret < 0) {
-			perror("setegid");
-			return EXIT_FAILURE;
+			PERROR("setegid");
+			goto write_return;
 		}
 	}
-	if (data->uid != geteuid()) {
-		ret = seteuid(data->uid);
+	if (data.uid != prev_euid) {
+		ret = seteuid(data.uid);
 		if (ret < 0) {
-			perror("seteuid");
-			return EXIT_FAILURE;
+			PERROR("seteuid");
+			goto write_return;
 		}
 	}
 	/*
 	 * Also set umask to 0 for mkdir executable bit.
 	 */
 	umask(0);
-	sendret.i = (*data->cmd)(data->data);
+	ret = (*cmd)(&data);
+
+write_return:
+	sendret.ret = ret;
+	sendret._errno = errno;
 	/* send back return value */
-	writeleft = sizeof(sendret);
-	index = 0;
-	do {
-		writelen = write(data->retval_pipe, &sendret.c[index],
-				writeleft);
-		if (writelen < 0) {
-			perror("write");
-			return EXIT_FAILURE;
+	writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
+			sizeof(sendret));
+	if (writelen < sizeof(sendret)) {
+		PERROR("lttcomm_send_unix_sock error");
+		ret = -1;
+		goto end;
+	}
+	ret = do_send_fd(worker, data.cmd, ret);
+	if (ret) {
+		PERROR("do_send_fd error");
+		ret = -1;
+		goto end;
+	}
+	if (seteuid(prev_euid) < 0) {
+		PERROR("seteuid");
+		ret = -1;
+		goto end;
+	}
+	ret = 0;
+end:
+	return ret;
+}
+
+static
+int run_as_worker(struct run_as_worker *worker)
+{
+	int ret;
+	ssize_t writelen;
+	struct run_as_ret sendret;
+	size_t proc_orig_len;
+
+	/*
+	 * Initialize worker. Set a different process cmdline.
+	 */
+	proc_orig_len = strlen(worker->procname);
+	memset(worker->procname, 0, proc_orig_len);
+	strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len);
+
+	ret = lttng_prctl(PR_SET_NAME,
+			(unsigned long) DEFAULT_RUN_AS_WORKER_NAME, 0, 0, 0);
+	if (ret && ret != -ENOSYS) {
+		/* Don't fail as this is not essential. */
+		PERROR("prctl PR_SET_NAME");
+		ret = 0;
+	}
+
+	sendret.ret = 0;
+	sendret._errno = 0;
+	writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
+			sizeof(sendret));
+	if (writelen < sizeof(sendret)) {
+		PERROR("lttcomm_send_unix_sock error");
+		ret = EXIT_FAILURE;
+		goto end;
+	}
+
+	for (;;) {
+		ret = handle_one_cmd(worker);
+		if (ret < 0) {
+			ret = EXIT_FAILURE;
+			goto end;
+		} else if (ret > 0) {
+			break;
+		} else {
+			continue;	/* Next command. */
 		}
-		writeleft -= writelen;
-		index += writelen;
-	} while (writeleft > 0);
-	return EXIT_SUCCESS;
+	}
+	ret = EXIT_SUCCESS;
+end:
+	return ret;
 }
 
 static
-int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
+int run_as_cmd(struct run_as_worker *worker,
+		enum run_as_cmd cmd,
+		struct run_as_data *data,
+		uid_t uid, gid_t gid)
 {
-	struct run_as_data run_as_data;
-	int ret = 0;
-	int status;
-	pid_t pid;
-	int retval_pipe[2];
-	ssize_t readlen, readleft, index;
-	void *child_stack;
-	union {
-		int i;
-		char c[sizeof(int)];
-	} retval;
+	ssize_t readlen, writelen;
+	struct run_as_ret recvret;
 
 	/*
 	 * If we are non-root, we can only deal with our own uid.
 	 */
 	if (geteuid() != 0) {
 		if (uid != geteuid()) {
+			recvret.ret = -1;
+			recvret._errno = EPERM;
 			ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
 				uid, geteuid());
-			return -EPERM;
+			goto end;
 		}
 	}
 
-	ret = pipe(retval_pipe);
-	if (ret < 0) {
-		perror("pipe");
+	data->cmd = cmd;
+	data->uid = uid;
+	data->gid = gid;
+
+	writelen = lttcomm_send_unix_sock(worker->sockpair[0], data,
+			sizeof(*data));
+	if (writelen < sizeof(*data)) {
+		PERROR("Error writing message to run_as");
+		recvret.ret = -1;
+		recvret._errno = errno;
 		goto end;
 	}
-	run_as_data.data = data;
-	run_as_data.cmd = cmd;
-	run_as_data.uid = uid;
-	run_as_data.gid = gid;
-	run_as_data.retval_pipe = retval_pipe[1];	/* write end */
-	child_stack = mmap(NULL, RUNAS_CHILD_STACK_SIZE,
-		PROT_WRITE | PROT_READ,
-		MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | MAP_STACK,
-		-1, 0);
-	if (child_stack == MAP_FAILED) {
-		perror("mmap");
-		ret = -ENOMEM;
-		goto close_pipe;
+
+	/* receive return value */
+	readlen = lttcomm_recv_unix_sock(worker->sockpair[0], &recvret,
+			sizeof(recvret));
+	if (!readlen) {
+		ERR("Run-as worker has hung-up during run_as_cmd");
+		recvret.ret = -1;
+		recvret._errno = EIO;
+		goto end;
+	} else if (readlen < sizeof(recvret)) {
+		PERROR("Error reading response from run_as");
+		recvret.ret = -1;
+		recvret._errno = errno;
 	}
-	/*
-	 * Pointing to the middle of the stack to support architectures
-	 * where the stack grows up (HPPA).
-	 */
-	pid = clone(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2),
-		CLONE_FILES | SIGCHLD,
-		&run_as_data, NULL);
-	if (pid < 0) {
-		perror("clone");
-		ret = pid;
-		goto unmap_stack;
+	if (do_recv_fd(worker, cmd, &recvret.ret)) {
+		recvret.ret = -1;
+		recvret._errno = EIO;
 	}
-	/* receive return value */
-	readleft = sizeof(retval);
-	index = 0;
-	do {
-		readlen = read(retval_pipe[0], &retval.c[index], readleft);
-		if (readlen < 0) {
-			perror("read");
-			ret = -1;
-			break;
-		}
-		readleft -= readlen;
-		index += readlen;
-	} while (readleft > 0);
 
-	/*
-	 * Parent: wait for child to return, in which case the
-	 * shared memory map will have been created.
-	 */
-	pid = waitpid(pid, &status, 0);
-	if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
-		perror("wait");
+end:
+	errno = recvret._errno;
+	return recvret.ret;
+}
+
+/*
+ * This is for debugging ONLY and should not be considered secure.
+ */
+static
+int run_as_noworker(enum run_as_cmd cmd,
+		struct run_as_data *data, uid_t uid, gid_t gid)
+{
+	int ret, saved_errno;
+	mode_t old_mask;
+	run_as_fct fct;
+
+	fct = run_as_enum_to_fct(cmd);
+	if (!fct) {
+		errno = -ENOSYS;
 		ret = -1;
+		goto end;
 	}
-unmap_stack:
-	ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE);
-	if (ret < 0) {
-		perror("munmap");
-	}
-close_pipe:
-	close(retval_pipe[0]);
-	close(retval_pipe[1]);
+	old_mask = umask(0);
+	ret = fct(data);
+	saved_errno = errno;
+	umask(old_mask);
+	errno = saved_errno;
 end:
-	return retval.i;
+	return ret;
+}
+
+static
+int run_as(enum run_as_cmd cmd, struct run_as_data *data, uid_t uid, gid_t gid)
+{
+	int ret;
+
+	if (use_clone()) {
+		DBG("Using run_as worker");
+		pthread_mutex_lock(&worker_lock);
+		assert(global_worker);
+		ret = run_as_cmd(global_worker, cmd, data, uid, gid);
+		pthread_mutex_unlock(&worker_lock);
+
+	} else {
+		DBG("Using run_as without worker");
+		ret = run_as_noworker(cmd, data, uid, gid);
+	}
+	return ret;
 }
 
+LTTNG_HIDDEN
 int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 {
-	struct run_as_mkdir_data data;
+	struct run_as_data data;
 
 	DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d",
 			path, mode, uid, gid);
-	data.path = path;
-	data.mode = mode;
-	return run_as(_mkdir_recursive, &data, uid, gid);
+	strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
+	data.u.mkdir.path[PATH_MAX - 1] = '\0';
+	data.u.mkdir.mode = mode;
+	return run_as(RUN_AS_MKDIR_RECURSIVE, &data, uid, gid);
 }
 
+LTTNG_HIDDEN
 int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
 {
-	struct run_as_mkdir_data data;
+	struct run_as_data data;
 
 	DBG3("mkdir() %s with mode %d for uid %d and gid %d",
 			path, mode, uid, gid);
-	data.path = path;
-	data.mode = mode;
-	return run_as(_mkdir, &data, uid, gid);
+	strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
+	data.u.mkdir.path[PATH_MAX - 1] = '\0';
+	data.u.mkdir.mode = mode;
+	return run_as(RUN_AS_MKDIR, &data, uid, gid);
 }
 
 /*
  * Note: open_run_as is currently not working. We'd need to pass the fd
  * opened in the child to the parent.
  */
+LTTNG_HIDDEN
 int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid)
 {
-	struct run_as_open_data data;
+	struct run_as_data data;
 
 	DBG3("open() %s with flags %X mode %d for uid %d and gid %d",
 			path, flags, mode, uid, gid);
-	data.path = path;
-	data.flags = flags;
-	data.mode = mode;
-	return run_as(_open, &data, uid, gid);
+	strncpy(data.u.open.path, path, PATH_MAX - 1);
+	data.u.open.path[PATH_MAX - 1] = '\0';
+	data.u.open.flags = flags;
+	data.u.open.mode = mode;
+	return run_as(RUN_AS_OPEN, &data, uid, gid);
+}
+
+LTTNG_HIDDEN
+int run_as_unlink(const char *path, uid_t uid, gid_t gid)
+{
+	struct run_as_data data;
+
+	DBG3("unlink() %s with for uid %d and gid %d",
+			path, uid, gid);
+	strncpy(data.u.unlink.path, path, PATH_MAX - 1);
+	data.u.unlink.path[PATH_MAX - 1] = '\0';
+	return run_as(RUN_AS_UNLINK, &data, uid, gid);
+}
+
+LTTNG_HIDDEN
+int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid)
+{
+	struct run_as_data data;
+
+	DBG3("rmdir_recursive() %s with for uid %d and gid %d",
+			path, uid, gid);
+	strncpy(data.u.rmdir_recursive.path, path, PATH_MAX - 1);
+	data.u.rmdir_recursive.path[PATH_MAX - 1] = '\0';
+	return run_as(RUN_AS_RMDIR_RECURSIVE, &data, uid, gid);
+}
+
+static
+int reset_sighandler(void)
+{
+	int sig;
+
+	DBG("Resetting run_as worker signal handlers to default");
+	for (sig = 1; sig <= 31; sig++) {
+		(void) signal(sig, SIG_DFL);
+	}
+	return 0;
+}
+
+static
+void worker_sighandler(int sig)
+{
+	const char *signame;
+
+	/*
+	 * The worker will its parent's signals since they are part of the same
+	 * process group. However, in the case of SIGINT and SIGTERM, we want
+	 * to give the worker a chance to teardown gracefully when its parent
+	 * closes the command socket.
+	 */
+	switch (sig) {
+	case SIGINT:
+		signame = "SIGINT";
+		break;
+	case SIGTERM:
+		signame = "SIGTERM";
+		break;
+	default:
+		signame = "Unknown";
+	}
+
+	DBG("run_as worker received signal %s", signame);
+}
+
+static
+int set_worker_sighandlers(void)
+{
+	int ret = 0;
+	sigset_t sigset;
+	struct sigaction sa;
+
+	if ((ret = sigemptyset(&sigset)) < 0) {
+		PERROR("sigemptyset");
+		goto end;
+	}
+
+	sa.sa_handler = worker_sighandler;
+	sa.sa_mask = sigset;
+	sa.sa_flags = 0;
+	if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
+		PERROR("sigaction SIGINT");
+		goto end;
+	}
+
+	if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
+		PERROR("sigaction SIGTERM");
+		goto end;
+	}
+
+	DBG("run_as signal handler set for SIGTERM and SIGINT");
+end:
+	return ret;
+}
+
+LTTNG_HIDDEN
+int run_as_create_worker(char *procname)
+{
+	pid_t pid;
+	int i, ret = 0;
+	ssize_t readlen;
+	struct run_as_ret recvret;
+	struct run_as_worker *worker;
+
+	pthread_mutex_lock(&worker_lock);
+	assert(!global_worker);
+	if (!use_clone()) {
+		/*
+		 * Don't initialize a worker, all run_as tasks will be performed
+		 * in the current process.
+		 */
+		ret = 0;
+		goto end;
+	}
+	worker = zmalloc(sizeof(*worker));
+	if (!worker) {
+		ret = -ENOMEM;
+		goto end;
+	}
+	worker->procname = procname;
+	/* Create unix socket. */
+	if (lttcomm_create_anon_unix_socketpair(worker->sockpair) < 0) {
+		ret = -1;
+		goto error_sock;
+	}
+	/* Fork worker. */
+	pid = fork();
+	if (pid < 0) {
+		PERROR("fork");
+		ret = -1;
+		goto error_fork;
+	} else if (pid == 0) {
+		/* Child */
+
+		reset_sighandler();
+
+		set_worker_sighandlers();
+
+		/* The child has no use for this lock. */
+		pthread_mutex_unlock(&worker_lock);
+		/* Just close, no shutdown. */
+		if (close(worker->sockpair[0])) {
+			PERROR("close");
+			exit(EXIT_FAILURE);
+		}
+		worker->sockpair[0] = -1;
+		ret = run_as_worker(worker);
+		if (lttcomm_close_unix_sock(worker->sockpair[1])) {
+			PERROR("close");
+			ret = -1;
+		}
+		worker->sockpair[1] = -1;
+		LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret);
+		exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
+	} else {
+		/* Parent */
+
+		/* Just close, no shutdown. */
+		if (close(worker->sockpair[1])) {
+			PERROR("close");
+			ret = -1;
+			goto error_fork;
+		}
+		worker->sockpair[1] = -1;
+		worker->pid = pid;
+		/* Wait for worker to become ready. */
+		readlen = lttcomm_recv_unix_sock(worker->sockpair[0],
+				&recvret, sizeof(recvret));
+		if (readlen < sizeof(recvret)) {
+			ERR("readlen: %zd", readlen);
+			PERROR("Error reading response from run_as at creation");
+			ret = -1;
+			goto error_fork;
+		}
+		global_worker = worker;
+	}
+end:
+	pthread_mutex_unlock(&worker_lock);
+	return ret;
+
+	/* Error handling. */
+error_fork:
+	for (i = 0; i < 2; i++) {
+		if (worker->sockpair[i] < 0) {
+			continue;
+		}
+		if (lttcomm_close_unix_sock(worker->sockpair[i])) {
+			PERROR("close");
+		}
+		worker->sockpair[i] = -1;
+	}
+error_sock:
+	free(worker);
+	pthread_mutex_unlock(&worker_lock);
+	return ret;
+}
+
+LTTNG_HIDDEN
+void run_as_destroy_worker(void)
+{
+	struct run_as_worker *worker = global_worker;
+
+	DBG("Destroying run_as worker");
+	pthread_mutex_lock(&worker_lock);
+	if (!worker) {
+		goto end;
+	}
+	/* Close unix socket */
+	DBG("Closing run_as worker socket");
+	if (lttcomm_close_unix_sock(worker->sockpair[0])) {
+		PERROR("close");
+	}
+	worker->sockpair[0] = -1;
+	/* Wait for worker. */
+	for (;;) {
+		int status;
+		pid_t wait_ret;
+
+		wait_ret = waitpid(worker->pid, &status, 0);
+		if (wait_ret < 0) {
+			if (errno == EINTR) {
+				continue;
+			}
+			PERROR("waitpid");
+			break;
+		}
+
+		if (WIFEXITED(status)) {
+			LOG(WEXITSTATUS(status) == 0 ? PRINT_DBG : PRINT_ERR,
+					DEFAULT_RUN_AS_WORKER_NAME " terminated with status code %d",
+				        WEXITSTATUS(status));
+			break;
+		} else if (WIFSIGNALED(status)) {
+			ERR(DEFAULT_RUN_AS_WORKER_NAME " was killed by signal %d",
+					WTERMSIG(status));
+			break;
+		}
+	}
+	free(worker);
+	global_worker = NULL;
+end:
+	pthread_mutex_unlock(&worker_lock);
 }